This invention relates generally to control of motion of a tool along a path. In particular this invention relates to controlling the motion of a point associated with a tool along an oscillatory path in a single plane.
It is well known in seam welding and gluing operations to oscillate a tool about a path to distribute weld metal or adhesive over an area within which the path lies. In seam welding the oscillations effect a distribution of weld metal between the pieces to be joined. When the plane of the oscillatory path is fixed, special apparatus may be provided to effect oscillation of the tool as it is advanced along the path. Apparatus are known in seam welding which impart mechanical oscillation to a weld head as it is advanced relative to a seam. However, where work is carried out by more versatile devices such as numerically controlled machines and manipulators, the accommodation of a variety of work planes presents a difficult control problem.
It is known to superimpose an oscillatory motion pattern on a path vector to effect oscillation about the vector. However the plane of oscillation must be known at the time of storing the oscillatory pattern defining signals and sufficient position location signals must be stored to define the desired oscillatory pattern. Where the tool motion is effected by a manipulator controlled according to a stored program of motions created by manually positioning the manipulator and causing coordinate data of path defining positions to be stored, the programming effort to effect oscillation along a weld seam is unacceptable.